1997 RAV4 Total Loss?

I was recently rear-ended and had what I thought was actually minimal damage. The other car hit my spare tire and dented my back gate. No broken glass even. Now the body shop is telling me that the insurance may deem it a total loss because the "floor rolled." What does that mean? I'm absolutely devastated. I love my 1997 RAV4. I don't want a new car and the payment. I have just under 80,000 miles on my RAV. I don't know what happens next if they do rule it a total loss. I know I want get enough to buy a new car. How is that fair when some drunk young guy rams into me?